What does the west wind mean by blowing thin willows?

west wind: the wind blowing from the west. Refers to the autumn wind.

Li Bai's "Long March" in the Tang Dynasty: "In August, the west wind rises, and I want you to make the Yangtze River."

The words in Chen Weisong's Hundred-character Order to Send Zhou Qiuzhuo to Xingyang in the Qing Dynasty: "The west wind shines in the sunset, and the old crow crows on the dead tree."

In autumn, all the trees wither, and the willow leaves begin to fall, which is not as lush as in summer, so it is called thin willow.

Autumn wind blows the willow with fallen leaves.